Most vehicles that have electric power steering systems also employ position sensors to monitor and provide an active returnability capability. Thus, as a vehicle is being driven, an active return command may be generated and communicated to the electric power steering system. In fact, this active return command could be generated even while the vehicle was being driven in a straight direction. Unfortunately, if the position sensor developed an offset over time, this offset could accumulate and be reflected in the active return command. This could cause problems, such as component wear, wheel misalignment or steering pull. In order to reduce or prevent these problems from occurring, the vehicle could be brought into an automotive service center on a periodic basis where any accumulated position offset could be evaluated, and corrected if necessary, by a service technician.
One problem that exists with a service type of arrangement is that vehicle owners might have any accumulated offset corrected only after misalignment or component wear has occurred. Another problem that sometimes occurs is that, even though some vehicle owners have their vehicles serviced regularly, this positional offset may develop and accumulate during the times between their regular servicing. In general, it is desirable not to require periodic service for a system and in fact, this is often a requirement of the OEM.
In view of the above, it would be desirable to provide a method for monitoring and updating a position sensor over time.
A method for updating a sensor offset using a robust sensor learning algorithm wherein the method includes obtaining vehicle data signals; obtaining a position sensor data signal, the position sensor data signal being responsive to a stored positional offset data signal; determining whether algorithm initial conditions are satisfied; formulating a new positional offset data signal conditioned on satisfaction of the initial conditions; and storing the new positional offset data signal so as to combine the new positional offset data signal with the stored positional offset data signal and replace the stored positional offset data signal.
A medium encoded with a machine-readable computer program code for updating a sensor offset using a robust sensor offset learning algorithm, the medium including instructions for causing controller to implement the aforementioned method.